{ INFORMATICS.MCCME.RU
  Problem statement: http://informatics.mccme.ru/moodle/mod/statements/view3.php?chapterid=154
  Verdict: Accepted
}
uses 
	SysUtils, Math;
 
var
	a,b:longint;
 
function gcd(a,b:longint):longint;
 
procedure swap(var a,b:longint);
 
var
	t:longint;
 
begin
t:=a;
a:=b;
b:=t;
end;
 
begin
if a<b then swap(a,b);
while b>0 do begin
	a:=a mod b;
	swap(a,b);
end;
result:=a;
end;
 
begin
reset(input,'input.txt');
rewrite(output,'output.txt');
fillchar(a,sizeof(a),0);
read(a,b);
write(gcd(a,b));
end.